New seal ring fragmentation causes and prevention measures

mechanical security seals seal ring fragmentation is a common phenomenon of early failure . Graphite stationary ring main is broken off , ceramic , tungsten carbide ring is mainly Seals cracks and deformation . Graphite ring broken off , a serious leak sealing , sealing medium pressure greater than the pressure can not be guaranteed . Although ring crack , causing leakage increased, but in most cases, but also to maintain operation . Resulting graphite ring broken off for many reasons , mainly the following .
( 1 ) Rubber seals or PTFE V-ring and graphite ring and stationary ring seat fit too tight , graphite by squeezing , under the dynamic fragmentation .
( 2 ) Install the seal chamber and pump in shock when heavy or pump seal chamber heavily skewed .
( 3 ) the swing axis and the string exceeds the specified value.
( 4 ) seal water interruption friction dry friction, high temperature , sealing ring thermal cracking , but suddenly sent to seal water , violent contraction of the seal ring fragmentation .
Ring crack main reasons are:
( 1 ) carbide ring , there is a greater stress on moving ring operation, in force , under the combined effects of internal forces cracks . These cracks are diverging radially dense fine cracks.
( 2 ) Temperature: non-metallic materials for the seal ring ( such as ceramic , WC), due to thermal conduction is not good , the ring is very uneven temperature distribution , even in normal conditions, the temperature may reach several Baidu , the temperature difference due to the presence and, thus, thermal stress caused by thermal deformation . When the thermal stress reaches a certain level , resulting in stress exceeds the ultimate strength of the material . At this time, the sealing ring on brittle materials tend to produce surface cracking , thereby enabling the sealing surface of the friction and wear and tear and failure. Due to thermal deformation of the sealing surface will fit clearance distortion, thus increasing the leakage .
Ring face with carbide , due to the thermal expansion coefficients of these materials are small , and the substrate materials, the thermal expansion coefficient difference between the larger ( stainless steel carbide thermal expansion coefficient than 3 to 4 times ) , so when the sealing temperature l exceeds a certain value , it will cause surfacing carbide seal ring deformation or cracks.
Solving dynamic and static bad fragmentation and deformation effective measures , in addition to strictly control the quality of spare parts processing , careful installation and maintenance , enhance operational management , the guarantee can be fully cable seals face lubrication and cooling are important measures. However, in practice, not any time to ensure adequate lubrication and cooling , seal water pressure fluctuations , disruption and misuse of workers , will cause the seal to lose sufficient lubrication and cooling.